Corona Mountain is the final area Mario and F.L.U.D.D. visit in Super Mario Sunshine. The path to this area is opened after Mario and F.L.U.D.D. complete all of the game's Shadow Mario levels. Corona Mountain is where the final showdown against Bowser and Bowser Jr. takes place.
The volcano contains an area where Mario must jump across platforms. These platforms are of two types. One type is a spiked platform, where spikes rise up and then recoil every few seconds. The tips of the spikes are shown a tiny bit to inform the player of the coming spikes before they rise completely, giving the player a few moments to escape. Note that these spikes cause instant death (except in rare circumstances if the hit is angled correctly, although a lot of health is lost), so timing is crucial. The other type is a platform that is covered in fire. It doesn't cause death immediately, but since the player is knocked upwards from the fire and back down when damaged, the player would likely lose a life anyway. This fire can easily be doused with F.L.U.D.D., but it will ignite again after a period of time.
The player must also avoid Cheep Cheeps that lurk in the lava, which can jump up and knock Mario into the lava. There is also an area where Mario must steer a boat to the other side of a sea of lava. Falling into the lava results in instant death. If the boat collides with anything, it will sink into the lava. Surprisingly, although the boat is made of mud, no harm will come to it if the player avoids the obstacles. The final part of Corona Mountain is using the Rocket Nozzle to blast up onto clouds to reach Bowser's spa. Unlike the other areas, Corona Mountain does not have episodes and is merely an obstacle course, followed by the final battle.
There are only ten Blue Coins throughout the entire mountain. The first blue coin is on a safe platform and can be obtained with relative ease. The other nine are in a circle formation around the platform at the end of the sea of lava, where the player has to equip the Rocket Nozzle. These nine coins can be obtained by steering the mudboat around the platform.
To access Corona Mountain, the player has to complete episode 7 (the Shadow Mario episodes) for each of the seven main areas of the game. In other words, episodes 1-7 have to be completed (with the exception of the first episode of Bianco Hills).
Episode 1: Blue Coins
Mario must collect 10 blue coins, one of them located at the start, and the other nine of them in certain places in the lava pool. If Mario touches the lava or spikes, or hits a wall or rock while in the boat, he automatically loses a life. Corona Mountain's only Shine Sprite counts as one of the Delfino Plaza sprites.
The hot spring at the foot of Isle Delfino's mountain is relaxing, but the lava caves, which open on the plaza, are forbidden for public safety.
"Corona" means "crown" in Italian, Spanish and Latin, and can also refer to the superhot plasma atmosphere that surrounds the sun. Because the rest of the locations of Isle Delfino have Italian names, the lava-filled volcano's allusion to the sun's heat may have merely been an afterthought or coincidence when "corona" was chosen for the mountain that crowned the "head" of the dolphin-shaped island.
Names in other languages